Information recording disks such as magnetic recording disks used, for example, in "hard disks," compact disks, etc. have a structure where a recording layer is formed on the surface of a substrate which is made of a metal or dielectric material. In making a magnetic disk used in a hard disk, a substrate of aluminum (Al), or other suitable metal or dielectric material is first coated with a nickel-phosphorus (NiP) layer. Next, an undercoat metal film of suitable material is deposited on a surface of the substrate and then a recording layer made from a thin magnetic film of suitable material is deposited on the metal film layer. The recording disk is completed by depositing a protective layer over the recording layer.
The protective layer must be composed of a durable film which has lubricating properties in order to shield the recording layer from impact and harsh environments. For example, sputtered carbon films (carbon films which have been deposited by sputtering) are commonly used as protective layers.
In a conventional fabrication process, the recording layer is deposited onto the substrate surface at relatively high temperatures (for example, about 200.degree. C.-250.degree. C.) to ensure that the recording layer has a high coercive force. It is important that the recording layer have good magnetic properties to provide reliable transfer of data to and from the magnetic recording layer. On the other hand, the protective layer is deposited at lower temperatures of, for example, about 100.degree. C.-150.degree. C. Thus, before the protective layer can be deposited, the recording disk must be cooled to a suitable temperature for deposition.
Conventionally, such cooling has been accomplished by natural heat loss, or radiation, from the recording disk. Natural heat loss, however, can be a time-consuming process as temperatures do not readily decrease in the vacuum environment commonly employed in the fabrication of information recording disks. Consequently, manufacturing "throughput" and, potentially, recording disk quality may be adversely affected.